1. Field of the Invention
This invention relates to a bottom flange running gear of a monorail overhead hoist or crane, and more particularly, to a bottom flange running gear having load-bearing running wheels on both sides of an I-shaped running rail. Front and rear lateral guide rollers of the running gear are mounted on vertical axles and are in contact with the running rail. A unilateral or one-sided load is applied to the running gear by a traction motor. The I-shaped running rail can also be a box girder having bottom flanges projecting from the sides, which flanges can be used as running rails for the running wheels.
2. Background Information:
When the load supported by a crane or hoist oscillates, monorail bottom flange running gears having only one pair of running wheels tend to make nodding movements in the direction of travel. Likewise, when there is a transverse oscillation of the load, the running wheel on one side of such running gears is lifted up. This lifting is practically impossible to prevent when the running gear travels around curves. For cranes or overhead travelling cranes with large wheel bases and wide gauges or track widths, load oscillations do not affect the traction behavior of the crane in the same manner as they affect monorail running gears. One type of running gear is disclosed by German Laid Open Patent No. 36 27 358. To prevent nodding movements, the running gear can be connected by means of a beam or bar with an additional running gear. For crane carriages travelling on the top flange of a beam, guide rollers in contact with the top, bottom and side of the flange can prevent a lateral oscillation of the crane carriage. The traction motor located in the center of the beam does not cause any tilting moment on the crane carriage.